Emergency services from the London Ambulance, Met Police and the LFB were all scrambled to the incident on Tuesday evening.
The LAS mobilised a full complement of there HART team and the LFB also sent a five fire engines and a rescue unit to assist in the recovery of the female who been pushed into the river after being attacked by a man.
The woman was trapped in mud in the River Cray in Pitch black freezing conditions
Crews used a mud lance that injected compressed air around the injured woman creating an air pocket which makes it easier to release her. She was then given oxygen therapy before being rushed to the hospital.
The man was later found following a search by officers and was arrested.
A spokesman for the Met Police said they were called at 8.49pm on Tuesday, 19 January to reports of a woman in the River Cray, off Brooks Way in Orpington.
Officers attended along with London Ambulance and London Fire Brigade. The woman reported being assaulted by a man who pushed her into the river.
She was taken to hospital where her condition was assessed as not life-threatening.
A 35-year-old man was arrested on suspicion of actual bodily harm. He remains in custody at a south London police station.
The victim and suspect were known to each other.
Enquiries into the circumstances are ongoing.